1. Prior Art
The following tabulation is some prior art that presently appears relevant:
US Patent NumberUS Patent Issue DatePatentee7,594,735B2Sep. 29, 2009Kang et al.7,652,216Jan. 26, 2010Sharrah et al.6,841,941Jan. 11, 2005Kim et al.7,393,120Jul. 1, 2008Kang et al.7,771,077Aug. 10, 2010Miller8,096,674Jan. 17, 2012Matthews et al.7,517,109Apr. 14, 2009Kim et al.7,880,100Feb. 1, 2011Sharrah et al.7,722,209May 25, 2010Matthews et al.7,540,625Jun. 2, 2009Matthews et al.6,017,129Jan. 25, 2000Krietzman7,997,756Aug. 16, 2011Rorick
This application relates to powering electrical circuitry in a flashlight tail cap, while still also being able to power the light in the head of the flashlight, without requiring any additional electrical connections beyond the conductive metal body of the flashlight housing. As LED lights fill more and more applications sometimes additional functionality is required. This additional functionality then, in turn, sometimes requires circuitry in the tail cap of a flashlight. Consider LED flashlights. Traditionally they have had a simple electrical switch on either the side or the tail of the flashlight. Note that the end of the flashlight that emits light is often called the head and the opposite end is called the tail. A tail cap refers to the cap or lid that screws on the tail end of the flashlight. The tailcap is removable to allow batteries to be inserted. Note that some designs have the head of the flashlight unscrew to insert batteries instead of having the tail be removed.
As flashlights have advanced through the years various tailcaps have been used as noted in the prior art cited above. A brief summary of these tailcap switches is that the simplest of them are just open or closed switches. More advanced models introduced mechanical means of selecting different modes of operation including different dimming levels by having complicated mechanical switching paths built into the flashlight. These complicated switching designs required multiple electrical paths to exist between the electrical driver that provides electrical current to the LED and the tail cap switch or the selected setting in the tail cap. Having multiple electrical signals exist between the tail cap and the head is accomplished by several different methods in the prior art cited above including using multiple wires, using a flexible circuit, using a PCB, using a battery holder that provides connections to both sides, etc. to connect the electrical signals between the head and tail of the flashlight. These methods all increase the cost and complexity of assembly.
2. Advantages Over Prior Art
One thing is consistent with all of the prior art cited above: none of it solved the problem of how to have the tail cap provide more advanced levels of control of the flashlight without the burden of adding additional connections between the head and tail of the flashlight. While the methods cited in the prior art are certainly varied, they all take a fundamentally mechanical approach to the problem. The method disclosed in this patent takes a more electrical approach and, oddly enough, results in a much simpler mechanical design. This simpler mechanical design saves cost and increases reliability by reducing connectors. The method disclosed here also allows for more advanced circuits to be in the tail cap since power can now be provided.
Another advantage over the prior art is that when a mechanical switch is used to open and close the circuit that switch must be able to withstand the maximum current load. This raises the cost and typically also the size of the switch, which in turn can limit the minimum size of the light.